Photo: Yemenis inspect the site of an explosion near the old city of Sanaa, Yemen, Saturday, June 20, 2015 (AP)

SANAA, Yemen -- An Islamic State-claimed car bomb exploded outside a mosque in Yemen's capital Saturday, killing at least two people and wounding six amid the country's raging civil war, authorities said.

The bomb targeted the Qabat al-Mahdi mosque in Sanaa's old city, where Shiite rebels known as Houthis and others pray, security officials said. The Islamic State group claimed the attack on a Twitter account associated with the extremists, saying it targeted Shiite Houthis, who the Sunni extremists view as heretics.

The security officials, who gave the casualty figure, spoke on condition of anonymity as they weren't authorized to brief journalists.

This is the second Sanaa attack claimed by the Islamic State group's affiliate in Yemen this week. On Wednesday, a series of Islamic State-claimed bombings in the capital killed at least four people and wounded 60.

In March, just before a Saudi-led coalition began its airstrike campaign against the Houthis, the Islamic State affiliate in Yemen claimed responsibility for a series of suicide bombings in Sanaa targeting Shiites that killed at least 137 people and wounded 345.

The Houthis seized control of Sanaa in September and continue their advance across the country despite the Saudi-led airstrikes. Yemen's conflict pits the Houthis and their allies against an array of forces, including southern separatists, local and tribal militias, Sunni Islamic militants and loyalists of exiled President Abed Rabbo Mansour Hadi.

Yemen's exiled government under Hadi and the Houthis have failed to come to terms on even a temporary cease-fire.

Meanwhile Saturday, a Houthi border attack killed a Saudi soldier and wounded five in the southern Saudi region of Jizan, which shares a jagged mountain border area with Yemen, the Saudi military said. Since the Saudi-led airstrikes began, Houthis in Yemen frequently attack Saudi border guards with cross-border mortar fire.

Also on Saturday, Saudi-led airstrikes hit Sanaa International Airport and a nearby air force base, and struck targets in Aden, Lahj, Jawf and Saada, Yemeni security officials said.